This is an R13 conference grant application for support of the biennial international workshop on "Molecular Aspects of Myeloid Stem Cell Development and Leukemia." The workshop is the 6th in this continuing series since 1995 and is scheduled for May 1-4, 2005, at the Historic Inns of Annapolis, MD. The workshop routinely hosts about 40 invited speakers, with a total of approximately 100 participants. Leukemia is a disease of hematopoietic stem cells that undergo a block in differentiation and a deregulated expansion. The workshop focuses on genes located at translocation breakpoints in leukemia such as AML1, TEL, RARalpha, and MLL to name a few, as well as on genes that are aberrantly expressed due to epigenetic alterations or function abnormally due to mutation. There is no doubt that mutations or abnormal levels of these factors are causally related to the development and progression of leukemia. Murine gene-targeting studies and sequence analyses of patient samples have shown the critical importance of these same genes for normal hematopoiesis. It is currently believed that the functions of these factors intersect and are interdependent (combinatorial) in hematopoietic differentiation. However, the complexity of their activities within these overlapping networks makes it very difficult for any single investigator to gain a wide scientific and clinical perspective so as to fully understand their unique roles in leukemia pathogenesis. The overall goal of these biennial workshops is to bring together investigators who have expertise in complementing aspects of stem cell biology and myelopoiesis - from normal myelopoiesis to myeloid leukemias. Both basic and clinician scientists from both sides of the Atlantic have come together biennially for the opportunity to interact and discuss their latest findings in a very close and informal setting in Annapolis. The workshop brings together basic research scientists with expertise in specific hematopoietic regulators, e.g. transcription factors, and clinician investigators who work on leukemia in terms of both mechanisms and therapeutics, including those focused on transcription factors, signal transducers and cell cycle components dysregulated through genetic or epigenetic mechanisms. A primary aim of this biennial workshop is the exchange of information through informal presentations and extensive discussions. It includes the participation of young investigators (graduate students, postdoctoral fellows) in this field who comprise the majority of participants and have the opportunity to present their work as short oral talks or posters. Participants of the workshop routinely communicate that, from the workshop, they achieve a better understanding of the critical steps and factors that regulate both normal hematopoiesis and their impact and potential relevance in the clinical setting in terms of leukemia. This workshop uniquely brings together clinician investigators, basic scientists, young investigators, and clinical research fellows in a manner that truly promotes scientific communication in terms of open exchange of ideas, unpublished findings, development of collaborative research, and cross-fertilization between scientists doing basic research on stem cell and myeloid development and those involved in translational research, leukemia treatment and therapeutics.